The specific aims of the project are 1) To determine if the ability of the human somatosensory system to adapt or accommodate to a durative, unchanging, superathreshold vibratory stimulus declines with age; 2) to examine the form and extent of such changes; and 3) to investigate the implications this may have for discriminability of vibratory amplitude and/or frequency. The results of this research will provide information that will increase the understanding of age-related sensory and central nervous system changes, and could prove to be valuable for designers of tactile aids for vision-or hearing-impaired individuals. This research will be conducted as a well-controlled series of psychophysical experiments, using a modified method of limits to determine both detection and difference thresholds for 25 and 100 hz test stimuli under conditions of iso-frequency adaptation and in equivalent control conditions (no adapting stimulus).